April 2014
Beginner to intermediate
830 pages
15h 21m
Chinese
Content preview from Mathematica 錦囊妙計
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80
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第二章
預設以第一個元素作為基準值，並以
Less
指令進行比較。[Page-080]
習慣上最後一個引數用來設定選項。
在選項決定之後，
qsort2
指令用來進行大部分的工作，
partition
的用法來自於訣竅 2.10。
在 Mathematica 6 以 前 的 版 本 中， 並 未 提 供
OptionValue[]
指 令， 語 法 上 可 使 用
ReplaceAll
（
/.
）方式優先使用使用者的自訂選項，未設定的選項再替換為選項預設
值，在較早期的程式碼中經常見類似的用法。
使用預設行為及自訂選項測試此函數。[Page-081]
ch02.indd 80 2014/4/2 上午 03:32:52
2.17 建立可接受選項之函數
|
81
以下基準值的挑選及比較函數都使用自訂函數
對已排序的串列而言，
設定第一個元素為基準值會導致較差的效能，
因此隨機選擇基準值或許是較保險的用法
討論說明
當你的函數有許多不同選項時（Mathematica 的
Graphics
指令是一個不錯的範例），或
當預設選項足夠應付大部分使用者時，選項是比預設引數（見訣竅 2.16）更好的選擇，
而且選項可讓函數介面不至於包含太多低階細節而顯得過於凌亂。
有 時 候 並 不 是 你 自 己 的 函 數 要 使 用 選 項， 而
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I wanted to learn C and C++, but it didn't click for me until I picked up an O'Reilly book. When I went on the O’Reilly platform, I was astonished to find all the books there, plus live events and sandboxes so you could play around with the technology.Addison B.
I’ve been on the O’Reilly platform for more than eight years. I use a couple of learning platforms, but I'm on O'Reilly more than anybody else. When you're there, you start learning. I'm never disappointed.Amir M.
I'm always learning. So when I got on to O'Reilly, I was like a kid in a candy store. There are playlists. There are answers. There's on-demand training. It's worth its weight in gold, in terms of what it allows me to do.